Field of the Invention
The present invention generally relates to semiconductor devices and methods of fabricating semiconductor devices. More particularly, the present invention relates to a semiconductor device with a reinforced metal gate spacer, and to a method of fabricating a semiconductor device with a reinforced metal gate spacer.
Semiconductor devices, such as field effect transistors (FETs), continue to be minimized. The trend of down-scaling can be observed in various types of FETs, including a metal oxide semiconductor field effect transistor (MOSFET) and a complementary metal oxide semiconductor (CMOS). The miniaturization of semiconductor devices has led to various electrical and/or processing limitations, and manufacturers have developed various techniques for dealing with such limitations. For example, a transistor device with a polysilicon gate may exhibit disadvantageous boron penetration and depletion effects, which may result in inferior performance of the device. In order to deal with these drawbacks, some manufacturers adopt a gate-last process to replace the conventional polysilicon gate with a metal gate having a metal electrode. Moreover, to deal with shrinkage between adjacent gate structures, and drawbacks due to insufficient space between the adjacent structures, some manufacturers employ a method for self-aligning a contact structure.
For a transistor device having both a metal gate and a self-aligned contact structure, a mask layer is often formed to cover the metal gate prior to the formation of the self-aligned contact structure. The mask layer covering the metal gate prevents unnecessary contact between the metal gate and the self-aligned contact structure.
Known methods of fabricating a transistor having a metal gate and a self-aligned contact structure have drawbacks. For instance, steps for forming a self-aligned contact structure may include removing a mask layer covering the metal gate. With the miniaturization of semiconductor devices, however, there is an increased risk of unnecessary contact between the metal gate and the self-aligned contact structure.
The deficiencies of the prior art are overcome to a great extent by the inventions described herein.